| Plugin Title | Open DNS |
| Cloud | |
| Category | VPC Network |
| Description | Determines if TCP or UDP port 53 for DNS is open to the public |
| More Info | While some ports such as HTTP and HTTPS are required to be open to the public to function properly, more sensitive services such as DNS should be restricted to known IP addresses. |
| GOOGLE Link | https://cloud.google.com/vpc/docs/using-firewalls |
| Recommended Action | Restrict TCP and UDP port 53 to known IP addresses. |
- Log into the Google Cloud Platform Console.
- Scroll down the left navigation panel and choose the "Networking" to select the "Firewall rules" option under the "VPC network."
- On the "Firewall rules" page, select the "Firewall rule" which needs to be verified.
- On the selected "Firewall rules", if "TCP or UDP port 53 for DNS" are open to the public then the selected "Firewall rule" is not as per the best standards.
- Repeat steps number 2 - 4 to verify another "Firewall rule" in the network.
- Navigate to "VPC network" and choose the "Firewall rules" option under the "Networking" and select the "Firewall rule" which needs to be restricted to known IP addresses.
- On the "Firewall rules" page, click on the "Edit" button at the top and enter the "Source IP ranges" as per the requirements.
- Click on the "Save" button at the bottom to make the changes.
- Repeat steps number 6 - 8 to restrict TCP and UDP port 53 to known IP addresses.
